longest-palindromic-substring solution java

longest-palindromic-substring/Solution.java

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+// Accepted
+// Runtime: 24 ms
+// Memory Usage: 39.3 MB
+// Submitted: January 13th, 2021
+
+class Solution {
+    public String longestPalindrome(String s) {
+        int left = 0;
+        int right = 0;
+        int curMax = 0;
+        
+        for (int i = 0; i < s.length(); i++) {
+            // Check both single and double char palindrome
+            int len = Math.max(expandAround(s, i, i), expandAround(s, i, i + 1));
+            
+            // If palindrome substring found is larger, switch out (calculate new value range)
+            if (len > curMax) {
+                left = i - (len - 1) / 2;
+                right = i + len / 2;
+                curMax = len;
+            }
+        }
+        
+        return s.substring(left, right + 1);
+    }
+    
+    // Finds the largest palindrome at a specific area
+    public int expandAround(String s, int left, int right) {
+        // Ensure it doesn't expand outside boundaries
+        // Check that left and right character equal eachother
+        while (left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {
+            // Expand!
+            left--;
+            right++;
+        }
+        
+        return right - left - 1;
+    }
+}